Thermostat - is it necessary?

Platonic Solid

Founding Member
May 29, 2002
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CT-USA
While replacing the upper radiator hose on my 73 - 351C - 2V, I discovered that there is no thermostat. The previous owner lived in CA. Though the car is never driven in winter, I assume I should put a thermostat in (I'm in CT).

The standard thermostat is 192°, but I see Mustangs Unlimited also offers a 180°. Which one should I get? Or is it just fine leaving it without any thermostat?
 
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Cool, thanks. New 180° thermostat ordered.

One more question. The old lower radiator hose has a large spring in it, which I assume is to keep it from collapsing. The new hose has no spring. Can I assume that new hoses are better (or different), thus don't need this item?
 
it is for the rubber hoses. I don't know if the silicon hoses which are much stiffer need them or not. I would still put it in anyways. Dont want to collapse the either hose.
 
You need the thermostat - I recommend the 190 stock temp unit for the best performance. Make sure that you end up with the correct Cleveland specific thermostat with the hat on the bottom. The thread link below has a photo of the correct Cleveland thermostat.

Make sure you also have the brass washer (restrictor plate) that goes underneath the thermostat.

Ford 335 "Cleveland" Series Engine Forum: 351C getting hot.


Here's a link with info about the brass coolant restrictor plate and where to get them if you need one.

Ford 335 "Cleveland" Series Engine Forum: 351c Brass Coolant Restrictor - JEGS Substitute?
 
Lots of good info there - Thanks Hack.

I have confirmed that the restrictor plate is there.

I ordered the 180° Thermostat from Mustang Unlimited which looks like this: (which seems to be the popular choice in the linked threads)

FK333-B.jpg

The 192° one they offer looks completely different (and is half the price):

RT139-B.jpg

While I was there I also ordered a new Thermostat housing since the old one was just too nasty to be worth playing with. I got this one:

84858-B.jpg

Now that I look at that Mustang Unlimited page again, I probably should have gotten the chrome (Scott Drake) one for the same price (though it would look kinda stupid on my - much less than impressive - no chrome anywhere - engine). (Plus I've had mixed experiences with Scott Drake products) Here's a pic anyway:

84858C-B.jpg

Though I assume it will be fairly obvious, my shop manual doesn't show the correct thermostat insertion direction nor order of assembly. My guess is:
1. Large round portion of thermostat down towards restrictor plate
2. then gasket over that (with sealant - RTV or Gasket Ahdesive - on both sides of gasket)
3. then Thermostat housing - torq bolts to 12 ft. lbs.
 
I hate myths about cooling systems! :mad: Fast coolant flow will improve cooling, not reduce it.


Chrome water necks are notorious for leaking, so you may have saved yourself some trouble by not buying the chrome version.
 
Well it took 3+ weeks to get the correct thermostat from Mustangs Unlimited. Apparently they're in process of moving their Connecticut store to a larger building.

I removed the spring from the old lower radiator hose, but it is in sad shape. Both ends broke off and there's a very weak spot in the middle which will surely break when I attempt to manipulate it into the new hose. I'm tempted to just install the hose without the spring, but am concerned of the potential hose collapse/over heating issue. Anyone know where I can get a replacement?
 
Earl's makes spring inserts in AN sizes. I used their -10AN spring to keep the hose from collapsing in an air/oil separator I use in another car. I don't know if they make anything as big as you'd need. We have a hose shop in my local area that can fabricate up all kinds of custom hoses and fittings upon request. Perhaps a local shop can either make a spring or has something on hand to use.
 
It is VITAL that you use the unique 192° Cleveland style thermostat! This 'stat has a unique cup on the bottom that closes the opening in the restrictor plate, to allow the engine to cool properly.

th_351Cthermostat.jpg

The 180° one, that took 3 weeks to get, looks like this:

FK333-B.jpg


It really bugs me that every auto parts store in existence will give you the wrong thermostat for the 351C.
 
You can't break the laws of physics. Sorry. :)

I've worked on cars now for 34 years, and during that timeframe, I have *always* heard that a restriction is required, all the way back from my high school auto shop class, to the training I had while working at GM.

Here's the reason--it takes time to transfer the heat of the engine to the coolant, and then transfer that heat to the air via the radiator.

The restriction is required because if you allow the coolant to flow freely, it will not adequately absorb the heat from the engine, nor will it transfer that heat to the air.

A really good example might be a NASCAR engine--it's doubtful they run t-stats, but they surely run restrictors, and you can buy those restrictors on Summit's and Jegs' websites.

Here's an example from Milodon:

Milodon 16420 - Milodon Water Outlet Restrictor Kits

If you don't believe me or D.Hearne, just pull the t-stat on your car, and run it down the highway for, say, 20 miles or so at 65-70MPH and see what your results are . . .

:):):)